# Explain the role of chlorophyll and accessory pigments in capturing light energy for photosynthesis.

> IB DP Biology Standard Level (2023 syllabus) — C1.3 Photosynthesis · Explain · 4 marks

## Mark scheme (4 marks)

1. Chlorophyll and accessory pigments absorb light at different / specific wavelengths, broadening the range of the spectrum used for photosynthesis.
2. Chlorophyll a and b absorb red and blue light mainly, whereas accessory pigments such as carotenoids absorb wavelengths in between (green/yellow/orange regions).
3. Energy absorbed by accessory pigments is transferred to chlorophyll a (the reaction centre) by resonance energy transfer.
4. At the reaction centre, chlorophyll a uses the absorbed energy to excite electrons to a higher energy level, which then enter the electron transport chain, enabling the light-dependent reactions to proceed.

## Key terms

- [chlorophyll](https://www.gradenine.co.uk/glossary/chlorophyll)
- [accessory pigments](https://www.gradenine.co.uk/glossary/accessory-pigments)

## Related

- [Revision notes for IB DP Biology Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-the-role-of-chlorophyll-and-2c96698e) · Published by Druglandscape Ltd.